Various proposals have been made with the aim of achieving required capacity using as little input energy as possible in an air-conditioning system or the like in which a refrigerator is used. Envisioned examples of machines that require input energy include compressor drive units and fan drive units.
The refrigeration cycle apparatus described in Japanese Patent Application No. H05-31045299 gives three examples of devices to which energy is inputted, namely, a compressor, an outdoor fan, and an indoor fan. Optimization control is carried out with focus on: the change ΔW in the total amount of input energy required in correspondence to a combination of the change ΔF in frequency of the compressor, the change ΔNo in the rotating speed of the outdoor fan, and the change ΔNi in the rotating speed of the indoor fan; and the change ΔQ in the capacity of the heat exchanger that changes in corresponding fashion.
In other words, with this refrigeration cycle device, a combination of change in rotating speed and/or frequency is set in advance for three control targets, i.e., the compressor, the outdoor fan, and the indoor fan used in a refrigeration cycle device. The change ΔW in the total amount of input energy required in correspondence to the combination of change and the change ΔQ in the capacity of the heat exchanger that changes in corresponding fashion to the combination of change are each calculated for each combination by computational processing. A combination is specified from among the combinations of the change ΔQ in the capacity of the heat exchanger and the change ΔW in the total amount of input energy, the specified combination being one in which the capacity of the heat exchanger satisfies the requested capacity conditions and in which the change ΔW in the total amount of input energy is minimized, and optimization control is carried out in accordance with the change conditions of the frequency of the compressor, the rotating speed of the outdoor fan, and the rotating speed of the indoor fan which correspond to the combination.